Commercial Case Studies of Life Cycle Cost Reduction of ARD Treatment with Sulfide Precipitation

摘要

Sulphide-based precipitation of divalent metals has been shown to greatly reduce life cycle costs and waste generation for the treatment of acid rock drainage (ARD) at mine sites. BioteQ's ChemSulphide~R process has been applied in multiple countries and continents and has proven to be a more cost effective solution than HDS or LDS lime plants on their own. Two case studies are presented in which the ChemSulphide~R process has been applied to reduce the life cycle cost of water treatment at sites facing active ARD treatment in perpetuity. The case study examines the lessons learned and causes of plant downtime at the Wellington Oro water treatment plant. The plant, which has been operating for over five years, has continually been able to meet strict discharge requirements for cadmium and zinc while entirely eliminating the production of waste sludge, however mechanical and secondary process issues had reduced plant availability. Lessons learned and mitigation methods that are currently being implemented are presented and discussed. The second case study looks at the ChemSulphide~R plant installed upstream of a HDS lime neutralization plant treating ARD at the Yinshan Mine in China. The plant selectively recovers copper as a commercial grade concentrate with the net revenues largely offsetting treatment costs to achieve both economic and environmental benefits. The net present value of the savings generated by the ChemSulphide~R plants at Wellington Oro and Yinshan are also analysed and discussed.